1. Field Of The Invention
The present invention generally relates to systems for monitoring motor vehicle traffic conditions on highways and, more particularly, to an improved traffic congestion information system for use by drivers in avoiding areas of traffic congestion.
2. Description Of The Prior Art
A number of systems now exist that monitor traffic conditions and transmit traffic information to individual motor vehicles. A typical system of this type is described in U.S. Pat. No. 4,792,803 to Madnick et al. In the Madnick system, an information receiving and analyzing computer accepts a variety of inputs from different traffic condition monitors, such as vehicle counting devices (i.e., proximity sensors buried in the pavement), video cameras mounted along the highways, and human inputs such as verbal traffic reports from the ground and aircraft, or accident reports. Since the reliability of such "anecdotal" data can vary from source to source, these human inputs must be evaluated by human beings and inserted into the system. The system then synthesizes and transmits over the airwaves a verbal traffic message for each of sixteen geographical "zones" designated within the overall traffic monitoring area. In a motor vehicle equipped with a suitable receiver, a driver presses one of sixteen pushbuttons at the receiver to activate the verbal traffic message corresponding to a specific zone of interest.
Although the traffic information provided by such conventional traffic monitoring and reporting systems as described in Madnick can be of some use to motor vehicle operators, it appears that the usefulness of the information is limited by certain operational drawbacks and inefficiencies of the conventional systems. For example, the narrowness of the broadcast bandwidths allocated for transmitting conventional traffic messages or reports limits the number of messages that can be transmitted at one time. Consequently, only a limited number of geographical zones may be designated or available within a given broadcast bandwidth. Moreover, traffic patterns within some zones typically are not uniform. As a consequence, there can be many different forms of congestion within a zone, which suggests the need to broadcast more than one message for that zone. Conversely, there may be no congestion in a number of zones, in which case no traffic messages or information would have to be broadcast with respect to those zones. In other words, individual drivers can select messages from among the zones, but cannot discriminate with messages from particular areas within the zones. Consequently, from one viewpoint, drivers utilizing the present traffic monitoring systems are subject to "information overload," wherein a plurality of zone-wide messages are received but only a few of the messages are of interest to particular drivers. From another viewpoint, however, there is a need to provide drivers with more useful information regarding traffic conditions within the zones.
As another example of information overload, conventional traffic monitoring and reporting systems do not take into account the direction of travel of the motor vehicle. For example, if a motor vehicle is traveling Westbound, the driver has no particular interest in receiving Eastbound traffic information. However, the Eastbound information is provided anyway. Consequently, the drivers using such a system are provided with more information than they require.
On the other hand, in order to assist a driver with avoiding traffic congested areas ahead, it is critical to provide information so that the driver may devise an alternative routing. For example, if a message is received that describes congestion ahead, a driver should be able to act on that message and formulate an alternative route around the congestion. However, as illustrated by the Madnick patent, no provision for formulating alternative routing information is provided by the conventional traffic monitoring and reporting systems.
Moreover, in order to use congestion or alternative routing information effectively, if such information were to be made available, a driver would have to be familiar with the locale and street names in order to take advantage of the information. For example, if a driver were to hear an audio message such as "heavy congestion on Main Street" but did not know the location of Main Street, then such information would not be effectively used. Consequently, a critical need exists for a traffic congestion information system which provides useful information on congestion ahead in a form which allows either an automated system or a driver to devise alternative routing to get around the congestion. As disclosed in more detail below, the present invention provides such a system.